Telephone system



March 5, 1929. M, s z 1,704,111

' TELEPHONE SYSTEM Filed Spt. 25, 2 Sheet et 1 imwmz March 5, 1929. M. B. STAZAK TELEPHONE SYSTEM Original Filed Sept. 23, 1926 2 Sheets-Sheet mon battery subscriber answer during a ringing period. The ringing apparatus is also used for signaling a called magneto line as will be more fully hereinafter described. A sleeve relay SL and an auxiliary sleeve relay SUL are also provided. To the right of Fig. 1, Part 2, I show a called common battery substation B terminating at the exchange in a line circuit L, comprising a line relay LR, cut oil relay CO, multiple answering acks J and the multiple line lamps SS. I also show a called magneto substation I) terminating at the exchange in a line circuit L which comprises a line relay Lll, cut oil relay CO multiple jacks J and line signal SS Having described in general the circuit arrangement I will now describe in detail the operation of the cord circuit of my invention. Assuming now that the common battery subscriber at the substation A initiates a call, the removal of the receiver at the substation closes an energizing circuit for the line relay LR of the line circuit L traced from battery through the winding of the relay LR, normal contact 2 of the cut oil relay CO, through the closed contact of the substation switchhook to ground at normal contact 3 of the cut off relay CO. The relay LR upon energization closes its alternate contact a to light the multiple line lamp signals SS which appear at a plurality of operators positions. Any one of a plurality of operators at the different positions at which the signals SS appear may answer the call to the exclusion of the others.

The operator associated with the cord C seizes the call by inserting the answering plug AP of the cord circuit G into the jack J of the calling line, establishing a circuit for the sleeve relay SL of the cord circuit C and the cut oil relay C of the line circuit L, traced from battery through the windings 5 and 6 of the sleeve relay SL,

conductor 7, normal contact 8 or the linlr disconnect relay Ll), the sleeve contacts of the connected plug AP and jack J to ground through the winding of the cut oil relay CO. The sleeve relay SL upon energization closes its alternate contact 9 and a substitute circuit is established for the relay SL throu h its low resistance windin 5 traced b b i from battery through the upper low resistance winding 5 of the relay SL its alternate contact 9, conductor 7 to ground through cut oil relay CO over the previously described path. Cut Oil relay CO upon energization opens its normal contacts 2 and 3 to open the energizing circuit of the line relay LR and the line relay LR upon deenergization' eil'aces the multiple line sig nals SS. The sleeve relay SL upon energizat-ion closes its alternate contact 10 establishing an energizing circuit for the en pervisory control relay SCB- traced from battery through the winding of the relay SOB, conductor 11 to ground at alternate contact 10 of the relay SL. The relay SCR upon energization closes its alternate contacts. 12 and 13 to close an energizing circuit for the supervisory relay SR traced from battery through the lower winding of the relay SB, conductor lei, alternate contact 13 of the relay SCH, conductors l5 and 16 through the winding 6 of the repeating coil RC, normal contact 17 of the ring back key RB, normal contact 18 of thelink disconnect relay Ll), ring contacts of the connected plug AP and jack J through the closed contacts of the substation switchhook of the calling substation A back through the tip contacts of the jack J and plug AP, normal contact 19 or the relay LD, normal contact 20 of the ring back key RB, winding a of the repeating coilRC, conductor 21, alternate contact 12 of the relay SCR, conductor 22 to ground through the upper winding of the supervisory relay SR and the supervisory relay SR upon energization opens its normal contact 23 and prevents the premature lighting of the answering supervisory signal AS. The closing of alternate contacts 24 of the relay SL and 25 or" the relay SCR establishes an energizing circuit lor the meter control relay MG traced from ground at alternate contact 24, conductor 26 through the winding of the meter control relay MQfits normal contact 27, conductor 28 alternate contact 25 of the relay SOB through the lamp AS to battery. The relay MO is energized over this circuit but the lamp AS does not light over this circuit due to the resistance 01" the relay MC. The relay MS upon energization closes its alternate contact 29 establishing a locking circuit for itself traced from battery through its alternate contact 29 through the winding of the relay MQconductOr 26 to ground at alternate contact 24 of the sleeve relay SL, and the meter control relay MG controls the operation of the meter relay ME for purposes as will be more fully hereinafter described.

The energization of the relays SL, SR, SCR and WC takes place as soon as the answering plug AP is inserted into the jack of the calling line. The operator now act-w ates her listening key LK and the closing of alternate contact 31 of the listening key LK establishes an energizing circuit for the listening relay LS, traced from battery through the winding of the relay LS, conductor 32 to ground at alternate contact 31 of the listening key LK. The relay LS upon energizing closes its alternate contacts 38 and 34 to'connect the operators set 0 to the cord conductors over conductors 35and 36,

normal contacts 37 and 38 of the operators cut out relay OR, alternate contactsBS-l and deenergized.

through the relay SE of the first cord tothe of the operators set associated 34 of the relay LS, and'conductors 39 and 4-0 to the tip and ring-conductors oi the cord circuit C. 7

Should another operator attempt to seize the call after the operator associated with the cord circuit C is connected thereto, the low resistance path through winding of the relay SL prevents the relay SL of the second cord from operating. The relay SL of the second cord failing to energize the relay SGR of the second cord remains Current flows from battery ring conductors of the multiple jack, into which the plug oi the second cord is inserted, then through normal contact 18 of the relay LB oi the second cord, normal contact l? of the key RB, winding b of the repeating coil RC conductor 16, winding of the clearing out relay CLR, normal contact 12 of the relay SCR, which relay of the second cord fails to energize due to the failure of relay Elli to energize, conductor 21, winding (0 of the coil RC, normal contact 20 of key liBynormal contact 19 of relayLl) to the tip conductors of the plug A l of the second cord and multiple jack J ot the calling line to ground through the relay SR of the first cord. The relay CLR of the second cord operates over this circuit and when the operator of the second cord actuates her listening key LK the operatofs cut out relay OR and the relay LS of the second cord are energized, relay OR energizing to ground at the alternate contact of the relay CLR of the second cord and relay LS energizing to ground at the key LK. The relay OR of the second cord energizes and opens its normal contacts 37 and 3S preventing the connection ond cord to the cord conductors. The second operator failing to receive a response when she answers knows that the call has been answered by another operator and withdraws the plug of her cord from the multiple jack of the calling line which allows relay CLR to deenergize allowing relay OR to restore and the restoring of the key LK allows relay LS to restore to normal.

The operator now inquires the wants'of the calling subscriber at thecommon battery. substation A and assuming tha't it'is the calledsubscriber at common battery substation E that is wanted the operator tests the called line as to its idle or busy condition by placing the tip of the calling plug GP to thesleeve ot the multiple jack J oi the called line B. It the line is busy the sleeve of the multiple jack J will be at a battery potential and this battery will extend from the tip of the plug GP, normal con tact all of the auxiliary sleeve relaySUL, normal contact 42 of the sleeve relay SL,-

test conductor L3 to ground-through the winding of a testrelay associated with the with the 'seoa *operators set 0. The energization ot'the test relay overthis path produces the cus toinary click in the operatorshead set which indicates the busy condition'oi the calledline.

Assuming that the called line is idle the operator inserts the calling plug OP into the multiple jack J of the called line establishing an energizing circuit for the sleeve relay st and the auxiliary sleeve relay SUL traced from battery through the Winding of the rela 1 SL conductor 46, through the winding of the relay SUL, conductors 47 and 4:8 through'ithe sleeve contacts of the connected plug (JP and jack J to ground t irough the winding of the cut off relay CO or" the line circuit L associated with the call-ed line. Cut oft relay CO, upon ei'iergization removes the substation control from the line relay Tilt of the line circuit L. The relay SL upon energizatron closes a substitute circuit for itself traced from battery through its winding, its

site: te contact 49, conductor 48, sleeve contaits ot' the connected plug GP and jack J to ground through the cut off relay CO. The relay SUL is shunted out at alternate contact lt) of the relay SL and relay SUL restores. The closing of alternate contact 50 of relay SL establishes an energizing circuit for the supervisory control relay SCH traced from battery through the winding of the relay SCR, conductor 51 to ground at alternate contact 50 of the relay SL. The relay SCH upon energizing closes its alternate contact 52 thus establishing an energizing circuit for the combined supervisory and ringing lamp SRL traced from battery through the lamp SRL, normal contact of theringing control relay RCR, conductor 54, alternate contact 52 of the relay SCH, normal contact 55 of the super visory relay SR, conductor 56 to: ground at normal contact 57 of the ringing trip relay HT. The lamp SRL is lighted over this circuit and remains lighted untilthe operator depresses the ringing key R- to signal fully depressed position to actuate the end 1 spring contacts to close their alternate contacts 58 and 59. The closing of alternate contact 590i the end-springs closes an energizing circuit' for the ringing control relay traced from battery through the windlager the ringing control relay 'RCR, conductors 60 andfi'l, normal 'cOntacttQ of the link disconnect relay Ll), conductor 63,

alternate contact thereby establishing a locking circuit for itself traced from battery through the winding of the relay RCR, conductors GO and (31, normal contact 62 of the link disconnect relay Ll), conductor 63, alternate contact 53 of the relay RCR, conductor 54 alternate contact 52 of the relay SCH, normal contact 55 of the relay SUE,

conductor 56 to ground at normal. contact 57 ot the ringing trip relay RT. The opening of normal contact 53 01 the relay RCR opens the circuit of the lamp SRL and the lamp SRL is now ctiaced.

The clo ing out the end spring contacts 58 and 59 and the energization ot relay RG12 now establishes an energizing circuit for the ringing interrupter relay RT traced from battery through the winding of the relay RT, conductor 66, alternate contact of the ringing control relay RUE. conductor 6?, alternate contacts 59 and 58 of the end spring contacts conductor (i l, normal contact 55 of the relay SR, conductor 56, to ground normal contact 57 or" the ringing trip relay RT. The relay R1 is energized over this circuit and closes its alternate contact 68 which connects ringing current from the generator G to the called line and gives the subscriber thereat an instantaneous first ring and when the pressure is released from the ringing key plunger it assumes its indicating position. The end springs 58 and 59 also assume their normal position and the closing of normal contact 59 of the end springs now connects the constantly rotating interrupter l in circuit with the ringing interrupterrelay BIL traced from battery through the winding ol the relay lll, conductor 66, alternate con tact 65 of the relay RC3, conductor 67 to ground through the constantly rotating interrupter l and the ringing interrupter relay ltl is energized and dcenergized over this circuit to intermittently apply ringing current to the called. line B. The ringing circuit which extends current to the called line may be tracml from the generator (I: through altcrnate contact 69 of the depressed ringing keyplungcr, conductor '70, through the winding T1 of the ringing trip relay RT, conuuctor 72, alternate contact 68 of the ringing interrupter relay El alternate contact e 2 of the relay SL, normal. contact all of the relay Sill) tip contacts of the connected plug GP and jaclt J through the condenser and call bell the ring contacts of the connected jack J and plug GP, alternate contact 73 of the relay RI to battery and ground through alternate contact 74 of relay R1,

at the called. substation B, back through A circuit -for short circuiting the winding 43 of the repeating coil RC is formed to prevent the discharge of the condensers across the called line from giving the calling subscriber at the substation A a disagreeable click in his receiver. The short circuit or shunt about the winding d of the repeating coil RC is traced from normal contact 73 of the relay R1 to the point 76, con- (luctor 79, through alternate contact 77 of the r conductor 78 through the sawin 5 2 of the repeating coil RC to 76 The lischa-rgc oi the condenser oi? the called line during each silent period has a tendency to momentarily energize the supernsory relay SR to open its normal. contact to open the locking circuit of the ringing control relay RCR to prematurely interrupt the ringing currentto the called lino but upon each deenergization of relay Til the closure of its normal contact 179 cr nice-ts battery 80 through normal contact 119 over conductor 81 in parallel with the energized ringing control relay RCR, to make the relay EUR sluggish in releasing and the s 'd relay RCR remains energized during this momentary interruption of normal contact of the supervisory relay SR due to the discharge of the condenser of the called line during the ringing of the called subscriber to prevent the premature interruption of the ringing current. The calling subscriber also given a distinctive revertive ringing tone which indicates to him that the called subscriber is being signalled. This signal extends from the generator G over conductor 82 to alternate contact 83 of the relay RT conductor 84 to the tip condoctor of the cord circuit C to the calling subscriber ol' the substation A. The called subscriber at the substation B in response to his call signal removes his receiver from the switchhook and should the subscriber remove the same during a ringing period the combined generator and battery flow through the winding 71 of the relay RT causes the relay RT to operate and the relay RT upor.v energizing opens its normal contact 57 which interrupts the locking circuit of the ringing control relay RC3 and the relay RUB upon deenergizing opens its alternate contact 65 which opens the circuit from the constantly rotating interrupter I to the ringing interrupter relay RI and the relay RI thus decnergizes to prevent furthe' application of ringing current to the called line. The clos ing of normal contacts 68 and 73 of the relay RI now establishes an energizing circuit for the supervisory relay Sl t traced from buttery through its lower winding, alternate contact 85 ojt relay SCH, conductors 86 and 78 through the winding d of the repeating coil. RC, normal contact 73 of relay RI and ring contacts oi the connected plug Cl? and ack J, through the closed contacts for the relay OR traced from of the substation switchhook contact back through the tip contactsoi the connected jack J and plug Cl? normal'contact 41 of rupter relay RI, through the winding c of the repeating coil RC, conductor 87, alternate contact 88 of relay SCH, conductor 89 to ground through theupper winding of the relay SR.

Should the called subscriber at the substation B remove his receiver in response to, his call signal during the silent period the removal of the receiver at the substation B will bring about the energization of the supervisory relay SR over a path just described. Relay SRT upon energizing opens its normal contact to open the locking circuit of the ringing control relay ROB, and the ringing control relay RCR upon deenergizing opens its alternate contact to disconnect the constantly rotating interrupter T from the ringing interrupter relay RT thus preventing further application of ringing current to the called line.

The subscriber at the common battery substation A and the called subscriber at the common battery substation B are now in conversational circuit, and the talking cir cuit may be traced over the heavily marked conductors.

Should. the operator of the cord circuit C attempt to listen in on the established connection just described by actuating her listening key LK, the closure of alternate contact 31 of the key LK brings about the energization of listening relay LS. The relay LS uponenergizat-ion closes its alternate contact 123 establishing an energizing circuit battery through the relay OR, alternate contact 31 of the key LK, conductor 200, alternate contact 201 of relay SR, conductor 202, alternatecontact 123 of relay LS, conductors'12 l and 125 to ground at alternate contact 23 of relay SE. The relay OR operates over this circuit andthe opening of its normal contacts 37 and 38 prevents the operators set 0 from beingiconnected to the cord conductors. e p I Assuming that the subscribers have finished their conversation they replace their receivers upon their respective switchhooks. The replacing of the receiver at the substation A opens the energizing circuit for the supervisory relay SR and thevclosing of its normal contact 90 closes an energizing circuit for the link disconnect relay LI) tracedfrom battery through the winding of the relay LD, conductor 91, normal contact 90 oftherelay SR, conductor 92, alternate contact 93 of relay SUB, conductors 94: and 51 to ground at alternate contact 50 of the sleeve relay SL. The opening of normal contact 8 01": the relay LD opens the energiz ing' circuit of the sleeve relay SL butdueto the closing of alternate contact 8 of relay LD the relay SL remains'energized by current flowing from battery through its upper winding 5, its alter ate contact 9, conductor 7, alternate'contact 8, resistance 95, conductor 9l, normal contact 90 of relay SR, conductor 92, alternate contact93 of relay SCH and conductors 94 and 51 to ground at alternate contact 50' of relay SL. The meter controlrelay MC and the relay SCR remain energized as the sleeve relay SL is held up over a circuit just traced. The opening of normal contact 8 or relay 'LD interrupts the circuit of the cutoff relay C0 of the line circuit L and therelay CO restores to normal placing the line relay LR of the line circuit L again underthe control o-f thesubscriber at the substation A which permits the subscriber at the substation A to i1ninediately recall and light the multiple line signals SS, and this recall may be answered by any operator before which the multiple line signals SS appear The relay SR upon restoring" to normah closes its normal contact 23 which closes a circuit for the answering supervisory lamp AS traced from battery through the lamp alternate contact 25 of relay SCI? conductors28 and 95 to ground at normal contact23 of the relay SB. The called subscriber at the substationBrepIao ing his receiver upon the switchhook opens the energizing circuit; of the supervisory re lay SR" at the switchhook contacts and the closing of ltSilOIHlfil contact 55 again'closes a circuit for the combined calling supervisory andringing control lamp SRL traced from battery through the lamp'to ground at normal contact '57 of the relay RT. The operator of thecord circuit C noting the two lighted supervisory lamps AS and SRL withdraws the plugs AP and CPoi the cord C from the respective acks J and J. The witl'idrawal of the plug AP from the jack J of the calling line does not affect any of the apparatus of the cord circuit but when the callingplug OP is withdrawn from the jack J of the called line the energizing circuitof the sleeve relay SL is opened and the opening of alternate contact 50 of the relay SL opens the energizingcircuit of the relay SOR and the relay SCH upon deenergization opens its alternate contact 52 to eftace the signal SRL. The opening of alternate contact 50, of therelay SL5 also opens the en ergizing circuit of the link disconnect relay LD and the relay LD upon. deenergization opens the circuit of the sleeve relay SL at alternate contact 8, and the relay SL upon denergization opensthe energizing circuit of the relaySCR at alternate contact 10 of the relay SL, and the relay SCH upon deenern'ization opens its alternate contact 25 to ellace the answering supervisory signal AS. The, opening of alternate contact 24:

of the relay SL opens the energizing circuit of the meter control relay MC but the relay due to its slow to release construction and the meter relay MB is now energized over a circuit just traced from battery through the winding of the relay MR, conductor 96, alternate contact 97 of the relay MC to ground at normal contact 98 of the relay SL. The meter relay upon energization closes its alternate contact 99 to close a circuit through the meter magnet MM from battery through alternate contact 99 of the relay MB to ground through the winding of the meter magnet MM. The meter magnet is energized and deenergized to operate the register associated with the meter magnet to register call The apparatus of the cord circuit C used in establishing a connection between the calling subscriber at the substation A and the called subscriber at substation B is new at normal, and available for use in establishing other connections.

Assuming that a call has been extended to the called substation B and the operator of the cord C has depressed the ringing plunger to connect ringing current to the called line and that the subscriber at the substation A replaces his receiver upon the switchhoolr before the called subscriber at the substation B has answered the replacing of the receiver at the substation A opens the energizing circuit of the supervisory relay SP1. The supervisory relay SR upon deenergizing closes its normal contact 90 to establish an energizing circuit for the link disconnect relay LD over a circuit as previously described and the relay LD upon 'energization opens the locking circuit of the ringing control relay RGR at its normal con tact 652. The ringing control relay RCR upon deenergizing opens its alternate contact to disconnect the constantly rotating interrupter from the ringing interrupter relay RT disconnecting ringing current from the called line. The closing of the normal contact 53 of the relay RCR closes a circuit through the lamp SRL over a path previously described and the closing of normal contact 28 of the relay SR also brings about the lighting of the answering supervisory lamp AS. The operator noting the two lighted signals withdraws the answering plug AP and the calling plug GP from the respective jacks and the restoration of the apparatus of the cord circuit C is the same as previously described.

Assuming that the callin subscriber at the substation A and the called subscriber at the substation B are in conversational circuit as before described and that another operator attempts to listen in: she is prerented from connecting her operators set 0 to listen in on the connection. If this operator inserts the answering plug AP of another cord in the multiple jack of the calling line the battery through the lower winding of the supervisory relay SR of the cord of the established connection extends from the ring contact of the multiple jack into which the plug of the second cord has been inserted over the ring conductor of the second cord through the winding of the relay CLR of the second cord back to ground through the upper winding of the supervisory relay SR of the first cord. The relay CLR of the second cord upon energization closes its alternate contacts 100 and 101 to bring about the energization of the relay OR of the second cord when the listening key is actuated, and the opening of normal contacts 37 and 38 of the relay OR of the second cord prevents the operators set 0 associated with the second cord from being connected to the established connection. Should the operator attempt to listen in on an established connection by the insertion of the calling plug of a cord pair into the multiple jacks of the established con nection the insertion will cause the relay SL of the second cord to operate and the operation of the relaySL will permit the relay CLR to operate from battery as before described in connection with relay CLR and the closure of alternate contacts 131 and 180 oi the relay CLR' of the second cord will bring about the operation of relay OR of the second cord when the operator actuates her listening key. The opening of normal contacts 37 and 38 of the relay OR of the second cord will thus prevent this second operator from listening in on an established connection.

Assuming now that the magneto subscriber at the substation C initiates a call the subscriber thereat operates the hand generator and current from the hand generator thereat operates the line relay LR through normal contacts 110 and 111 of the cut off relay C0 The line relay LE is momentarily energized by current from the hand generator to close its alternate contact 112 thus establishing a circuit for the line signal The alternate contact 112 of line relay LR is locked in its 01? normal position to maintain the line signal SS lighted and the operator in response to line signal SS inserts the answering plug AP of the cord circuit G into the jack J of the calling line, closing an energizing circuit for the cut oil relay C0 of the line circuit L associated with the calling magneto substation C, over a circuit traced from battery through the windings 5 and 6 of the sleeve relay SL, conductor 7, normal contact 8 of the link disconnect relay LD, the sleeve contact of the connected plug AP and jack J to ground through the cut oil relay C0 The cut oil relay CO is energized over this circuit but key LK which brings about the energization' of the listening relay LS of the cord C b-ycurrent flowing from battery through the winding of the relay LS, conductor 32 to ground at alternate contact 31, of the listening key LK, and the closure of the alternate contacts 33 and 34 of the relay LS connects the operators set 0 to the cord conductors.

. The operator now inquiresthe wants of the calling subscriber at the magneto substation C and assuming that it is the magneto substation D that is wanted the operator tests the line as to its idle or busy condition. Assuming that the line is idle the operator in serts the calling-plug Cl into the jack J of the wanted line closing an energizing circuit for the cut oil relay CO associated with the line circuit L and the auxiliary sleeve relay SUL traced from battery through the winding'ot' the relay SL, conductor as, through the winding of the relay SUL, conductors 17 and 48, the sleeve contacts of theconnect ed plug'CP and jack J to ground through the cut oil relay CO. The cut oil relay Ct) and the relay SUL- are energized over this circuit but the relay SL remains at normal.

The operator now applies the proper ringing frequency to the called line to operate the call signal at the substation B, and assuming that the generator G is the proper generator frequency for aetuatingthe call bell at the called substationD the operator depresses the ringing key plunger associated with the ringing generator G to its fully depressedposition to actuatethe end spring contacts. The plosing of alternate contact 58 of the end spring closes an onergizing circuit for the ringing control relay RCR traced from battery through the winding of the relay ROB, conductors and 61, conductor 11 1, normal contact 115 of relay SCR, conductors 116 and 63, alternate contact 58 of the end spring contact-s, conductor 64, normal contact 55 of the relay SR, conductor 56 to ground at normal contact 57 of the ringing trip relay RT. The closure of alternate contact of the relay RCR estab lishes an energizing circuit for the ringing interrupter relay RI traced from battery through the ringing interrupter relay Bl, conductor 66, alternate contact 65 of the relay RCR, conductor 67, alternate contacts 59 and 58 of the end spring contacts, conductor 64, normal contact 55 of supervisory relay SR, conductor 56 to ground at normal contact 57 01 the ringing trip relay RT. Ringing current is connected to the called The relay CO upon through line due to the energization of ringing interrupter relay RI, the path for ringing current being traced from generator G, through alternate contact 69 of the depressed ringing key plunger, conductor 70, through the winding 71 of the relaylitT, conductor 72, alternate contact 68 of the ringing interrupter relay RI, a ornate contact 11 of the relay SUL, tip contacts of the connected plug GP and jack J through the call bell the called jack 5 73 and 7a of relay R1 to battery and ground.

Ringing current is thus consubstation D back the r ng contacts ol the connected and plug GP, alternate contacts nected to the called substation D and as long as the ringing key plunger is held in its fully depressed position ringing current is applied to the called line. lVhen the ringing key plunger which connects the ringing generator G is released it moves to its indicating positionv allowing, the end spring contacts to assumetheir normal position and the opening of alternate contact 58 of the end spring contacts allows the relay ltCR to deencrgize and the relay RCR upon deenergization opens its alternate contact 65 to open the energizing circuit of theringing interrupter relay RT. Each time that the operator applies ringing current to the called line the l-rey plunger associated with the generator G is depressed to its fully actuated position in which positionthe end spring contacts again closed to operate the ringing control relay RGR andringing interrupter relay R1; to impress ringing current upon the called line. The operator supervisesthe magneto connection by actuatsubstation D answers further depression of:

the ringing'lrey plunger associated with the generator G is stopped. The calling mag neto subscriber C and the called magneto subscriber D are no v in conversational circuit the talking circuit being tracedjover 'ing her listening key from time to time and when the called-subscriber at the magneto signal the magneto subscriber at the subg station C actuates his hand generator and the current from the hand generator extends from the tip oi the aclr J and plug AP, through normal contact 19 of the relay LD,

normal contact 20 the ring back key RB,

through the winding a of the repeating coil RC, conductor 21, normal contact 12 of relay SCR, conductor 120, through the winding of the relay CLR, conductor 16,

winding Z2 of the repeating coil. RC, normal contact 17 of the ring back key RB, normal contact 18 of the link disconnect relay Ll), the ring contacts of the connected plug AP and jack J to the hand generator at the substation C. The relay CLR energizes over this circuit and establishes an energizing circuit for the supervisory relay SR traced from battery through the lower winding ot the relay SR, conductor 14, normal contact 13 of relay SOB, conductor 121 through the resistance 122, normal contact 123 or the listening relay LS, conductor 12a to ground at alternate contact 100 of the relay SLR. The relay Sit upon energizing closes its alternate contact 23 to establish a locking circuit for itself? traced from battery through the lower winding of the relay SR, conductor 14-, normal contact 13 of r lay SCR, conductor 121, resistance 122, nor mal contact 123 of the relay LS, conductor 124, conductor 125 to ground at alternate contact 23 of the supervisory relay SE, The relay CLR deenergizes but the relay SR is held energized over the circuit just traced independent of the now restored relay Lit. The closing of alternate contact 23 of the supervisory relay SR establishes an energizing circuit for the answering supervisory signal AS traced from battery through the signal AS, normal contact 25 of the relay SCH, conductor 126, normal contact 127 of the relay CLlt, conductor 125 to ground at alternate contact s3 of the relay Silt. Supervisory signal AS is lighted over this circuit and indicates to the operator that the calling subscriber at the magneto substation C has replaced his receiver upon the switchhook and given the disconnect signal.

The called subscriber at magneto substation D after replacing his receiver upon the switchhook operates the hand generator thereat and the current from 'the hanc genera-tor operates the relay SLR. The current from the hand generator extending therelrom through the tip contacts of the connected jack J and plug GP, alternate contact 11 of the relay SUL, normal contact 68 of the relay RI, the winding 0 of the repeating coil RC, conductor 37, normal contact 88 of the relay SCH, conouctor 128, normal contact 129 of the relay RCR, conductor 130, through the winding oi'the reley SLR, conductor 78, through the winding (Z of the repeating coil BC, the ring contacts of the connected plug GP and jack d baclc to the generator 01 the substation l). The relay GLR is energized by this flow of current while the hand generator is being operated and the closure of its alternate contact 131 establishes an energizing circuit for the supervisory relay SR traced from battery through the lower winding of the relay SR", conductor 132, normal contact 85 of the relay SCH, conductor 133, normal contact 134 of the listening relay LS, conductor 135 to ground at alternate the relay RT.

gized over the circuit just traced independent of the relay CLR. The closure of alternate contact of the relay SR closes a circuit for the supervisory signal SRL traced from battery through the lamp SRL, normal contact 53 of the ringing control relay RCR, conductor 54-, normal contact 52 of the relay SGR, conductor 136, normal 1.

contact 13"- of the ringing control relay EOE, conductor 138, normal contact-139 of the relay SLR, conductor 14:0, alternate contact 55 of the relay SR, and conductor 56 to ground at normal contact 57 of The lamp SRL is lighted over tl'iiscircuit and gives the operator a di onnect signal which indicates to her that the called subscriber at substation D has replaced his receiver upon the switchhook. The operator noting the two lighted signals AS and SRL withdraws the plugs AP and Cl? from the respective aclrs J and J 'llhevwithdrawal of the plug GP from the jar-l: J brings about the deenergization of the relay SUL of the cord C and the cut oil relay C0 of the line circuit L The operator new actuates her listening key LK closing an energizing circuit for the listening relay LS traced from battery through the winding of the relay LS, conductor 32 to ground at alternate contact 31 of the listening key LK. The relay LS upon energization opens its normal contacts 123 and 13 1 and the opening of normal contact 123 opens the locking circuit for the supervisory relay SR and the supervisory relay SR upon deenergization opens the circuit for the supervisory lamp AS at alternate contact 23 and lamp'AS is now eliaced. T he 0 iening of normal contact 134i of the listening relay LS opens a locking circuit for the supervisory relay SR and the super isory relay SR upon deenergization opens its alternate contact 55 to eti'ace the supeiyisory signal SRL. The operator now restores her listening key L1"; and thereby opens the energizing circuit for the relay LS and the apparatus used in establishing the connection between the magneto substation C and the magneto substation l) is now at normal and available for establishing other connections.

Should a connection be established between a common battery substation A and a magneto substation D the operation of the circuit can be readily "followed from the previous description, and likewise the connection between substations C and B is readily apparent from the foregoing description.

While I have described my invention in one specific form, I do not wish to be limited to the same, as changes and modifications will readily suggest themselves to those skilled in the art, and I, therefore, aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

Having described my invention what I claim is new and desire to secure by United States Letters Patent is:

1. In atelephone system of the character described including common battery and magneto telephone lines, universal link circuits for use in interconnecting said lines as calling and called lines, an operators set, operator controlled means comprising a listening key, a listening relay operable upon the actuation of said operator controlled means for connecting said operators set to a calling one of said common battery lines,

and relay means in said link circuits including a clearing out relay adapted to be energized upon the connection of a second link circuit to a calling line, for preventing the connection of a second operators set to said calling line subsequent to the connection of said first operators set to said line.

2. A telephone system of the character described including common battery and magneto telephone lines, universal link circuits for use ininterconnecting said lines as calling and called lines, an operators set, a

listening key and a listening relay, said' relay operable upon the actuation of said listening key for connecting said operators set toa calling one of said common battery lines, and relay means in said link circuits including an operators relay, and a clearing out relay adapted to be energizedupon the connection of a second link circuit to a calling line to cause sa1d operators relay to operate upon the actuation of sa1d listening key to prevent the connection of a second operators set to said calling line subsequent to the connection of said first operators set to Saidline.

3. In a telephone system of the character described including common battery and magneto telephone lines, universal link circuits for use in interconnecting said lines as calling and called lines, an operators set, a listening key and a listening relay, said relay operable upon the actuation of said listening key for connecting said operators set to a calling one of said lines, and relay means in said link circuit including anoperators relay, and a clearing out relay adapted to be energized upon the connection of a second link circuit to a calllng line to cause said operators relay to operate upon theactuation of said listening key to prevent the connection of a second operators set to said common battery calling line subsequent to the'connection of said first operators set to said line.

4-. In a telephone system of the character described including, a cord circuit adapted to connect subscribers lines having either common battery Olll'liLgIlGliO substations in conversational circuit, an operators set, a listening key and a listening relay, said relay operable upon the actuation of said listening key for connecting said operators set to a calling one of said lines, an opera tors cut out relay, and relay means in said cord circuits operating when a second cord adapteduto be operated intermittently over.

a circuit controlled by, said ringing control relay to connect, ringing current to a called subscribers line, switching means controlled by said ringing control relay for short circuiting a winding of said repeating coilto prevent the discharge of the condensers of said called line from affect ng said calling line. 1 i

6. A telephone system of the character described including common battery and local battery subscribers telephone lines, an operators universal cord circuit including a repeat-ing coil for use vin'connecting said lines, a source of ringing current, a relay adapted to be energized and deenergized to intermittently apply said ringing current to acalled subscribers line, a ringing control relay controlling the operation of said first relay, and switching means controlled by said ringing control relay -for short circuit ing a winding of said repeating coil to prevent the discharge of said called subscribers line from atlecting the calling line.

7 A telephone system of the character describedincluding common battery and local battery subscribers telephone lines, an

operators universal cord circuit, including eration of said ringing interrupter relay, switching means controlled by said ringing control relay, said switching means of said ringing control relay adapted upon the deenergization of the ringing interrupter relay to cause a shunt to be placed about a winding of said repeating coil to prevent the discharge of said calledsubscribefis line trom ali'ecting the calling line.

8. A telephone system of the characterdescribed including common battery and local battery subscribers telephone lines, an operators universal cord circuit for interconnecting said lines, a repeating coil for said cord circuit, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and deenergizing said ringing interrupter relay r'or intermittently applying ringing current to a called subscribers telephone line, a ringing control relay controlling the operation 01 said ringing interrupter relay, a supervisory relay controlled over said called line, said supervisory relay controlling said ringing control relay, switching means controlled by said ringing control relay operative upon the deenergization of said ringing interrupter relay to prevent the premature deenergization of said ringing control relay.

9. A telephone system of the character described including common battery and local battery subscribers telephone lines, an operators universal cord circuit for interconnecting said telephone lines, a repeating coil for said cord circuit, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and deenergizing said ringing interrupter relay for intermittently applying ringing current to a called line, a ringing control relay controlling the operation of said ringing interrupter relay, a supervisory relay controlled over said called line "for controlling said ringing control relay, switching means op placed about a winding of said repeating coil to prevent the discharge of said called subscribers line from affecting the calling line, and other means operative upon the deenergization or said ringing interrupter relay adapted to prevent the premature deenergization of said ringing control relay.

10. A telephone system oi the character described including common battery and local battery subscribers telephone lines, an operators universal cord circuit for interconnecting said subscribers telephone lines, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and deenergizing said ringing interrupter relay for intermittently applying ringing current to a called subscribers line, a ringing control relay controlling the operation oi said ringing interrupter relay,

an initial energizing circuit for said ringing control relay, a locking circuit for said ringing control relay, a supervisory relay controlled over said called line and adapted to energize to interrupt said locking circuit to cause the deenergization of said ringing control relay, and switching means opera,- tive upon the deenergization of said ringing interrupter relay adapted to prevent the premature deenergization of said ringing control relay.

11. A telephone system of the character described including common battery and local battery subscribers telephone lines, an operators universal cord circuit for interconnecting said telephone lines, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and decnergizing said ringing interrupter relay for intermittently applying ringing current to a called line, a ringing control relay controlling the operation of said ringing interrupter relay, an energizing circuit for said ringing control relay, and switching means operative upon the deenergization of the said ringing interrupter relay for connecting a source of battery current in parallel with said ringing control relay to render said ringing control relay sluggish to prevent the premature deenergization of said ringing control relay.

12. A telephone system of the character described including common battery and local battery subscribers telephone lines, an operators universal cord circuit for interconnecting said telephone lines, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and deenergizing said ringing interrupter relay for intermittently applying ringing current to a called common battery telephone line, a ringing control relay for controlling the operation of said ringing interrupter relay, a supervisory relay controlled over said called line, a ringing trip relay controlled over said called line, a locking circuit for said ringing control relay, said supervisory relay adapted to operate to interrupt said locking circuit when said ringing interrupter relay is deenergized, said ringing trip relay adapted to operate to interrupt the said locking circuit when said ringing interrupter relay is energized and switching means operative upon the deenergization of said ringing interrupter relay to prevent the premature deenergization of said ringing control relay. I

13. A telephone system of the character described including common battery and local battery subscribers telephone lines, an operators univesal cord circuit for interconnecting said telephone lines, a source of ringing current, a ringing interrupter relay, interrupter means for energizing and deenergizing said ringing interrupter relay for intermittently applying ringing current to a called line, a ringing control relay for controlling said ringing interrupter relay, a repeating coil for said cord circuit, a supervisory relay controlled over said called line, a ringing trip relay controlled over said called line, a locking circuit for said ringing control relay, said supervisory relay adapted to operate only when said ringing interrupter relay is in a deenergized condition to interrupt the said locking circuit and cause said ringing control relay to deenergize, said ringing trip relay adapted to operate only When said ringing interrupter relay is in an energized condition to cause the deenegization of said ringing control relay, and switching means operative upon the deenergization 'ofthe said ringing in terrrupter relay to cause a shunt to be placed about a Winding of said repeating coil to prevent the discharge of said called line from affecting the calling line.

Signed by me at Chicago, county of Cook and State of Illinois, this 21st day of September, 1926.

MICHAEL B. STAZAK. 

